Microwave data transmission apparatus

ABSTRACT

A microwave data transmission apparatus adapted to transmit and receive information by microwaves, which the identification tag is made smaller in size and lighter in weight to considerably improve the convenience in setting operation for use in many applications, can be applied for the production control within the factory or the control for entering and leaving the room by a person having an identification tag.

BACKGROUND OF THE INVENTION

The present invention relates to a microwave data transmission apparatuswhich is adapted to transmit and receive information by microwave.

Conventionally, the construction shown in FIG. 7 is used as a microwavedata transmission apparatus for transmitting and receiving informationby microwave.

In FIG. 7, an identification tag 2 is adapted to answer the fixedinformation stored therein through the microwave signal waves withrespect to a interrogator 1 when the interrogator 1 asks a questionthrough the microwave signal radio waves with respect to anidentification tag 2. The interrogator has therein a signal generator 3for generating the microwave signals, a transmitting antenna 4 fortransmitting into the air as the waves the signals coming from thesignal generator 3, a receiving antenna 5 for catching the waves fedfrom the identification tag 2, and a demodulator 6 for demodulating themicrowaves coming from the receiving antenna 5. Also, the identificationtag 2 has a receiving antenna 7 for catching the waves fed from theinterrogator 1, a demodulator 9 for demodulating the microwaves caughtby the receiving antenna 7, a signal generator 10 for causing thecarrier waves of the microwave band, a code generator 11 for fixedlystoring the code information to generate the code information signals inaccordance with the outputs of the demodulator 9, a mixer 12 (which maybe a modulator) for mixing the code information signals fed from thecode generator 11 with the carrier-wave signals fed from the signalgenerator 10, and a transmitting antenna 8 for transmitting the outputsignals of the mixer 12.

In the conventional microwave data transmission apparatus of theabove-described construction, the signals obtained from the signalgenerator 3 within the interrogator 1 are transmitted towards theidentification tag 2 from the transmitting antenna 4. The transmissionsignals are received by the receiving antenna 7 of the identificationtag 2 and continuously demodulated by the demodulator 9. The signalafter the demodulation functions as a controlling signal for controllingthe code generator 11 and the signal generator 10. The code informationsignals are fed into the mixer 12 from the code generator 11 by thecontrol of the signals after the demodulation. Also, the carrier wavesof the microwave band are fed into the mixer 12 from the signalgenerator 10. In the mixer 12, the carrier waves of the microwave bandare modulated by the code information signal. The modulated signals aretransmitted into the air with the waves towards the interrogator 1 bythe transmitting antenna 8 of the identification tag 2. In theinterrogator 1, the waves from the identification tag 2 are received bythe receiving antenna 5, and the fixed information stored in advance inthe identification tag 2 is fetched through the demodulation by thedemodulator 6.

However, as a signal generator 10 for transmitting the carrier waves ofthe microwave band is necessary without fail within the identificationtag 2 in the above-described microwave data transmission apparatus, apower-supply apparatus of comparatively large capacity is provided forthe driving operation of the signal generator 10. Thus, the constructionof the identification tag 2 is rendered more complex and larger in size.Also, in the conventional apparatus, no consideration is given to changethe memory contents of the code information in the code generator 11,thus resulting in an extreme limitation to flexibility and application.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide animproved microwave data transmission apparatus, wherein theidentification tag is made smaller in size and lighter in weight, toconsiderably improve the convenience in the setting operation for use inmany applications.

In accomplishing the above-described object, according to the presentinvention, there is provided a microwave data transmission apparatushaving a interrogator provided with a transmitting means fortransmitting microwave signals having a modulation period and anon-modulation period, and a receiving means for receiving microwavesignals, and an identification tag provided with a transmitting meansfor detecting the microwave signals sent from the interrogator to givethe modulation based on the data of the memory portion with respect tothe carrier wave during the non-modulation period of the microwavesignals to transmit the microwave signals after the modulation withrespect to the interrogator.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the present invention willbecome apparent from the following description taken in conjunction withthe preferred embodiment thereof with reference to the accompanyingdrawings, in which:

FIG. 1 is a circuit block diagram of a microwave data transmissionapparatus in accordance with a first embodiment of the presentinvention;

FIG. 2 is a wave-form diagram related to FIG. 1;

FIG. 3 is an electric circuit diagram of a power-supply built in CPUemployed in FIG. 1;

FIG. 4(a) to FIG. 4(f) is a wave-form diagram related to FIG. 1;

FIG. 5 is a block circuit diagram of a microwave data transmissionapparatus in accordance with a second embodiment of the presentinvention;

FIG. 6 is a wave-form diagram related to FIG. 5, and;

FIG. 7 is a similar diagram to FIG. 1, but, showing a conventionalmicrowave data transmission apparatus already referred above.

DETAILED DESCRIPTION OF THE INVENTION

Before the description of the present invention proceeds, it is to benoted that like parts are designated by like reference numeralsthroughout the accompanying drawings.

Embodiment 1

FIG. 1 shows a block circuit diagram of a first embodiment of amicrowave data transmission apparatus in accordance with the presentinvention.

Referring now to the drawings, there is shown in FIG. 1, a microwavedata transmission apparatus, which includes a interrogator 101 composedof a transceiver 21 and a transceiving antenna 22, an identification tag102 including a transceiving antenna, a demodulator and modulator 24, areceiving signal line 25, a transmitting signal line 26, and apower-supply built-in CPU 27. It is to be noted that the receivingsignal line 25 and the transmitting signal line 26 may be used by thesame signal line.

Also, FIG. 2 shows the waveform chart of the signal wave to be radiatedto the identification tag 102 from the interrogator 101. As shown inFIG. 2, the signal wave is composed of a power starting signal S1, acontrolling signal S2, and a non-modulation wave S3 (of storing data orthe like), so that the signal wave is repeatedly radiated at the periodτ.

The operation is as follows in the above-described microwave datatransmission apparatus.

First, a series of signal waves are radiated, which are repeated at theperiod τ shown in FIG. 2 from the transceiving antenna 22 of theinterrogator 101. The power starting signal S1 is one for starting thepower supply of the power built-in CPU 27 of the identification tag 102.As the identification tag 102 is mounted on the vehicle, baggage or thelike for a moving operation, the power supply is not required to benormally kept started. In order to make the identification tag 102smaller in size, the power consumption should to be smaller. Also, asthe interrogator 101 is adapted to be used in fixed specified positionsnear the gate of the parking lot, a robot of a production line or thelike, the power supply of the identification tag 102 is sufficient ifthe starting operation is performed only in a surveillance region calledthe range, over which the radiating waves of the interrogator 101 reach.Control the power consumption is controlled to minimum outside of theregion and the power consumption may thus be saved.

Then, the controlling signal S2 following the power starting signal is asignal for conveying to the power supply built-in CPU 27 whether theinstruction content of the interrogator 101 is the reading of datastored within the memory of the power supply built-in CPU 27 or is databeing stored in the memory. If the controlling signal S2 is the readcontrolling signal of the data within the memory, then non-modulatedwaves of a constant length are transmitted, following the controllingsignal S2. Also, if the controlling signal S2 is the write controllingsignal into the memory, the writing data are transmitted, following thecontrolling signal S2. If the CPU is designed so that the CPU mayperform the reading operation only with the power starting signal S1,the controlling signal for reading use may be omitted.

FIG. 2 shows how a series of signals are produced through amplificationmodulation of the carrier wave of a frequency f. Frequency modulation orphase modulation may be used as the method of the modulation withrespect to the carrier wave of the frequency f.

A series of signals, shown in FIG. 2, radiated from the interrogator 101are received by the transceiving antenna 23 of the identification tag102, and each of the signals is demodulated by the demodulator andmodulator 24 so that it is transmitted into the power-supply built-inCPU 27 through the receiving signal line 25. The power-supply built-inCPU detects the demodulated power starting signal S1 to start the powersupply, and sequentially fetches the data stored within the memory ifthe controlling signal S2 being continuously fed is a read signaldriving the demodulator and modulator 24 in accordance with the datacontents over the transmitting signal line 26. The non-modulated wavesreceived from the transceiving antenna 23 following the controllingsignal S2 by the driving operation are modulated by the reading data,which are read from the memory of the power-supply built-in CPU 27, andare radiated again from the transceiving antenna 23. The waves which aredemodulated and re-radiated by the demodulator and modulator 24 arereceived by the transceiving antenna 22 of the interrogator 101 and aredemodulated by the transceiver 21.

On the other hand, when the controlling signals S2 following the powerstarting signals S1 are write signals, the writing data signals beingsent following the controlling signals S2 are fed into the power-supplybuilt-in CPU 27 through the receiving signal line 25, and are writteninto a given region of a memory for the storing operation.

The data transmitting operation of the optional information writing orreading is performed by a series of operations with respect to theidentification tag from the interrogator 101. Also, the identificationtag 102 is adapted to start the power supply only when it is located inthe surveillance region of the interrogator 101, and to automaticallyturn off the power supply, except for that case to provide the condition"start waiting" so as to save the power consumption.

One example of the further concrete circuit construction of thepower-supply built-in CPU 27 is shown in FIG. 3, which includes a powersupply 271 such as a battery, storage battery or the like, an amplifier272 composed of a C-MOS operation amplifier and so on, a microprocessor273 for the C-MOS, a transistor 274, resistors 275, 276, 279, a NOR gate277 for the C-MOS, a capacitor 278, and a vibrator 281 of ceramic,crystal or the like.

In FIG. 3, power is always fed into the back-up terminals of theamplifier 272, the NOR gate 277, and the microprocessor 273. The back-upterminal for the microprocessor 273 is a terminal disposed to retain thememory data stored in an internal RAM. The power consumption by theseelements is an extremely small, being about 30 μW at the most, for a 3 Vinput power voltage. The amplifier input 272 is amplified up to thevoltage level necessary enough to drive the C-MOS NOR gate 277. The LOWlevel (earth potential) is outputted at a non-signal time from theoutput terminal. The comparator of the C-MOS, which is not shown, isdisposed on the output stage of the amplifier 272.

The waveforms ○a through ○f in FIG. 4 show the voltage waveforms of eachportion of the circuit of the power-supply built-in CPU 27 of FIG. 3.The operation of the power-supply built-in CPU 27 will be described infurther detail by the use of the voltage waveform of FIG. 4.

The microwave signal (FIG. 4 ○a ) from the interrogator 101 received bythe transceiving antenna 23 is demodulated (FIG. 4 ○b ) by thedemodulator and modulator 4, and is fed into the amplifier 272. Thetransistor 274 in a turn-off state as the two input terminals of the NORgate 277 are both low in level (earth potential) at the non-signal time.When the microwave signal is received, the output of the amplifier 272becomes high in level (power-supply potential) by such a power startingsignal as shown in FIG. 2, and the output of the NOR gate 277 becomeslow in level so that the base voltage of the transistor 274 is reducedin the base voltage to the turn-on state (FIG. 4 ○c ). As a result, thepower voltage is applied to the V_(DD) terminal (FIG. 4 ○d ) through thetransistor 274 to start generating the clock signals with theoscillation frequency of the vibrator 281 in the microprocessor 273 andthe signals moving from the low level into the high level are fed, whilethe capacitor 280 is being charged, into the resetting terminal to resetthe microprocessor 273. The microprocessor 273 starts the operation inaccordance with the built-in program from this time point to, first, setthe output terminal OUT1 into the high level. As the output terminal ofthe NOR gate 277 still maintains the low level even if the output of theother input terminal of the NOR gate 277, i.e., the output of theamplifier 272 becomes low in level, the power voltage is fed into theV_(DD) terminal, so that the microprocessor 273 continuously operates.Then, the microprocessor 273 watches the outputs of the amplifier 272fed into the input terminal IN in accordance with a built-in program.When the controlling signal S2 is judged to be a read control signal,the contents stored within the microprocessor are sequentially drawn outfrom the output terminal OUT2 of the microprocessor 273 as shown in FIG.4 ○f and are outputted into the demodulator and modulator 4. Also, whenthe controlling signal S2 is judged to be a write control signal, thewrite data S3 following the controlling signal is sequentially fed bythe input terminal IN and is stored into the memory of the CPU. The datastored in this memory is continuously retained by the power voltage tobe applied upon the back-up terminal even after the power supply of themicroprocessor 273 has been turned off through the turn-off spate oftransistor 274.

After the above-described series of operation are over, themicroprocessor 273 returns the output terminal OUT1 to the low level(FIG. 4 ○e ) in accordance with the built-in program. Thereafter, placedin an idle condition, the two input terminals of the NOR gate 277 bothreturn a low level, and the output of the NOR gate 277 becomes high toturn the transistor 278 off. Accordingly, the microprocessor 273 stopsits operation. Although the one embodiment of the power-supply built-inCPU 273 is described hereinabove, the various circuit constructions maybe embodied in addition within the range of the present invention.

An example of a automatic identification system for exchanging data bymicrowave data transmitting apparatus which uses the above-describedinterrogator and the identification tag will be described hereinafter.This type of apparatus may be used in production control within afactory, for warehouse control, for the gate control of a parking lot, acontrol for entering or leaving a room, or the like. Specifically inproduction control within a factory, a small-size identification tag ismounted on each part flowing onto the production line, and aninterrogator for reading the memory data of the identification tag isdisposed near the line.

The information on each part which comes close to the interrogator isread through the identification tag to control the flowing on the lineof the parts in accordance with the information stored therein. Theproduction control of the parts may be precisely performed in thismanner.

According to the first embodiment, various signals may be transmittedand received in time series comparison by the use of one type of theworking signal frequency only, so that the automatic identificationsystem having many functions may be realized, thus allowing the widerapplication as well as the extremely practical system may be realized.

Embodiment 2

FIG. 5 shows a block construction diagram of a second embodiment of amicrowave data transmitting apparatus in accordance with the presentinvention.

In FIG. 5, an interrogation member 301 is provided with a transceiver302 having a transmitting circuit for transmitting the waveformmicrowave signal shown in FIG. 6, a polarized wave separating andcomposing member 314 for transmitting by mutually different first andsecond polarized waves of the same frequency both the controllingmodulation signal 523 and the non-modulation carrier 524 shown in FIG.6. The mutually different polarized waves are considered, specifically,a combination between the right-hand circularly polarized wave and aleft-hand circularly polarized wave, and the combination between acircularly polarized wave and a linearly polarized wave, and thecombination between a linearly polarized wave of 0° direction and alinearly polarized wave of 90° direction. A transceiving antenna 313 fortransmitting and receiving the microwave signal with respect to the air(or from the air) is connected with the interrogator 301.

Also, an identification tag 401 has therein a polarized detachmentcomposing member 415 for detaching, in accordance with the polarizedwave, the microwave signals generated from the interrogator 301, ademodulator 416 for demodulating the controlling modulating signal 523,a modulator 417 for modulating the non-modulation wave 524 to be fedcontinuously in time series comparison into the controlling modulationsignal 523, and a signal processing member 418 composed of a circuit oflow power consumption of C-MOS IC and so on for carrying out each typeof signal processing operation. Also, a transceiving antenna 419 fortransmitting and receiving the microwave signal from the air (or withrespect to the air) is connected with the identification tag 401.

The operation of the above-described microwave data transmissionapparatus will be described hereinafter in detail.

The microwave non-modulation wave is modulated by the modulating signalas shown in FIG. 6 from the interrogator 301 and is transmitted as theradio wave through the transceiving antenna 313. The modulation signalshown in FIG. 6 has a controlling modulation signal 523 of the firstpolarized wave direction, for example, the right-hand circularlypolarized wave, and the non-modulation wave 524 of the second polarizedwave direction, for example, the left-hand circularly polarized wave,and is a signal to be repeatedly appeared with a constant period T. Theradio wave transmitted by the transceiving antenna 313 is received bythe transceiving antenna 419 on the side of the identification tag 401when the distance between the interrogator 301 and the identificationtag 401 becomes a certain value or lower, and the receivingelectric-field level becomes a certain amplitude or higher. The receivedsignal detected by the polarized-wave separating and composing member415. The controlling modulation signal 523 to be, first, fed isdemodulated by the demodulator 416 and thereafter is fed into the signalprocessing member 418. The signal processing member 418 remains in itsidle condition under a condition when the signal from the interrogator301 is not received. This idle condition means an inoperative conditionwhere the power consumption is of a minimum necessary to retain theinformation of the RAM inside the signal processing member 418, andpower is not fed in many circuits.

When the data information being retained in the identification tag 401is required, first, to be read under such a condition as describedhereinabove, the signal processing member 418 moves into the operatingcondition if the signal processing member 418 receives form thedemodulator 416 the signal 523a for power starting use of thecontrolling signal 523 of FIG. 6 from the interrogator 301. Theprocessing is recognized to be a reading operation of the datainformation by the signal detection of the next read instructing signal23b. The CPU within the signal processor 418 then feeds into themodulator 417 the data informated stored in the RAM by the recognitionfor the time of the following non-modulation carrier 524. The modulator417 modulates by the data information the non-modulation carrier 524received through the polarized-wave separating and composing member 415.The modulated waves are radiated towards the interrogator 301 from thetransceiving antenna 419 so that they are received through thepolarized-wave separating and composing member 415. The modulated wavesare radiated towards the interrogator 301 from the transceiving antenna419 so that they are received in the interrogator 301 by thetransceiving antenna 313. The received waves are detected in thetransceiver 302 to draw the data information stored within the signalprocessing member 418.

In order to change the data information retained in the identificationtag 401, the interrogator 301 transmits as radio waves the controllingmodulating signals 523 composed of the above-described polarized-wavedirection microwave signals through the transceiving antenna 313,thereafter transmits the writing data signals 524', composing of thesame first polarized-wave direction microwave signals, as the radiowaves from the transceiving antenna 313. When the writing data signals524' are transmitted as the radio waves from the transceiver antenna313, the antenna 419 of the identification tag 401 receives the radiowaves, and the demodulator 416 demodulates the received signals throughthe polarized-wave separating and composing member 415 to guide thedemodulation signals into the signal processing member 418. At thistime, the signal processing member 418 is moved into the operatingcondition by the reception of the power starting signal 523a of thealready preceding modulation signal 523 for control use, and knows thatit is adapted to perform the data information changing process by thesignal detection of the write instructing signal 523b' so as to re-writethe contents of the memory data retained in the internal RAM inaccordance with the demodulation signal. Although the example whereinthe read instructing signals used from the interrogator 301 during thereading operation is shown in the above-described construction, the readinstructing signal may be omitted if the CPU is designed to be read onlythrough the signal 523a for power starting use. Also, one-portioninterrogator may be used for exclusive reading use, but all theinterrogator may not be employed for both the writing and reading use.

The above-described microwave data transmission apparatus may be appliedfor the production control within a factory, for warehouse control, gatecontrol of parking lots, and the control for entering and leaving a roomby a person having an identification tag. For example, for use in theproduction control within the factory, a interrogator is mounted on eachpart, which has the individual data inputted previously in the memory,the data including the code numerals on the production line, the workingprocedure, the carrying routes, etc. The interrogators are disposed atthe major point locations on the production line. The interrogatortransmits the microwaves with respect to the identification tag disposedon each part flowing on the production line to read the internal data asdescribed hereinabove to output the control signal for controlling theflow of the line. As the microwaves penetrate plastic and lumber, theidentification tag is not particularly required to be disposed on thesurface of each part.

According to the second embodiment, the highly functional microwave datatransmission system where the identification tag may be made smaller inshape and lighter in weight because of low proper consumption may beprovided.

Although the present invention has been fully described by way ofexample with reference to the accompanying drawings, it is to be notedthat various changes and modifications will be apparent to those skilledin the art. Therefore, unless otherwise such changes and modificationsdepart from the scope of the present invention, they should be construedas being included therein.

What is claimed is:
 1. A microwave data transmission apparatuscomprising:an interrogator including,first transmitting means fortransmitting modulated microwave signals during a modulation period andnon-modulated microwave carrier signals during a non-modulation period,and first receiving means for receiving microwave signals; and anidentification tag including,a control processing unit having a built-inpower supply, said power supply being periodically rendered operationalupon receipt of a power starting signal transmitted during a firstsub-period of said modulation period to activate said processing unit, amemory portion, and transceiving means including second receiving meansfor receiving the modulated microwave signals sent from saidinterrogator during a second sub-period of said modulation period andfor receiving said non-modulated microwave carrier signals sent duringsaid non-modulation period, and second transmitting means includingmodulating means for modulating said received non-modulated microwavecarrier signals with data stored in said memory portion to providereturn microwave signals for transmission back to said interrogator. 2.A microwave transmission apparatus comprising:an interrogatorincluding,transmitting means for transmitting modulated microwavesignals and non-modulated microwave carrier signals having in timesequence a period of mutually different first and second typepolarizations during a modulation period and non-modulation period,respectively, and receiving means for receiving microwave signals ofsaid second type polarization; and an identification tag including,asignal processor periodically being rendered operational upon receipt ofa power starting signal during a first portion of said first typepolarization transmission from said interrogator, said power startingsignal activating said signal processor, a memory, and transceiver meansfor detecting the modulated microwave signals of said first typepolarization and the non-modulated microwave carrier signals of saidsecond type polarization received from said interrogator and formodulating said non-modulated microwave carrier signal based on data insaid memory to provide a return modulation signal for transmission tosaid interrogator, said return modulation signal being microwave signalsof said second type polarization, wherein said first and second typepolarizations comprise mutually different type circular polarizations.3. The apparatus as defined by claim 2 wherein said circularpolarization types includes right-hand and left-hand circularpolarizations.
 4. A microwave data transmission apparatus comprising:aninterrogator including,transmitting means for transmitting in timeseries a modulation signal and a non-modulation carrier signal, saidmodulation signal having a frequency f and a first polarization, saidnon-modulation carrier signal having said frequency f and a secondpolarization, and receiving means for receiving a modulation signalhaving said frequency f and said second polarization; and a responderincluding,detection means for detecting said modulation signal havingsaid frequency f and said first polarization which is outputted fromsaid interrogator, a memory portion, modulation means for modulatingsaid non-modulation carrier signal based upon data stored in said memoryportion to create a return signal, said return signal having saidfrequency f and said second polarization, and transmitting means fortransmitting said return signal to said interrogator.
 5. The apparatusas defined by claim 4 wherein said first and second polarizationscomprise mutually different type circular polarizations.
 6. Theapparatus as defined by claim 4 wherein one of said first and secondpolarizations comprises a circular polarization and the other of saidpolarizations comprises a linear polarization.
 7. The apparatus asdefined by claim 4 wherein said first and second polarizations comprisemutually different type linear polarizations.
 8. The apparatus asdefined by claim 7 wherein one of said mutually different type linearpolarizations comprises a 0 direction linear polarization and the otherof said mutually different type polarizations comprises a 90 directionlinear polarization.
 9. The apparatus as defined in claim 4 wherein saidresponder further includes a control processing unit having a built-inpower supply, said power supply being periodically rendered operationalupon receipt of a power starting signal transmitted from saidinterrogator during a sub-portion of said modulation signal.